Non-destructive evaluation (NDE) method has been popularly used for thermal diagnosis of building envelop in order to retrofit old buildings, detect civil engineering structures and accredit new buildings. The infrared thermography technique has been widely applied in the NDE method. In order to develop new solutions for diagnostic of local thermal performance, experiments were carried out on two cases of multilayer walls. Experimental results of emissivity, temperature, and heat fluxes will be shown and analyzed in this article. The main originality of this work is to try to compute the front face temperature response to transient periodic heating by computing the front face pulse response. Such front face pulse response is obtained by a deconvolution method and a TSVD inverse method. The thermal properties of the wall will be characterized through the opotimization method based on the thermal quadrupoles model.

This paper presents a new hybrid image scanning technique for concrete crack evaluation. The hybrid image combining vision and infrared (IR) thermography images can improve crack detectability as well as reduce false alarms. The hybrid image scanning system is developed by integrating vision camera, IR camera, continuous-wave (CW) laser and mechanical scanning jig. The CW laser continuously generates thermal waves, and the vision and IR cameras simultaneously record the corresponding vision and IR images on the region of interests (ROI) of a target structure. By spatially scanning the hybrid images with the limited field of view (FOV) using the scanning jig, even large ROI can be effectively inspected. Then, the corresponding image processing algorithm including the distortion calibration and image conversion to spatially integrated FOV images is proposed. The proposed system and algorithm are experimentally validated using a lab-scale concrete specimen with artificial macro-cracks (≥ 500 μm), micro-cracks (< 500 μm) and a fake crack. The experiment results reveal that the hybrid image scanning technique successfully visualizes various macro- and micro-cracks, and no positive false alarm is indicated.

In this paper we discuss the application of Lock-in and Step heating techniques for defect detection in nuclear graded concrete structures. In case of Step Heating optimization of heating period is carried out by analyzing the Signal to Noise Ration and defect detectability. Also Thermal Signal Reconstruction is carried out for noise reduction and the results are compared. In Lockin Thermography depth probing is done by varying the frequency and the Signal to Noise Ratio and defect detectability limits are studied.

Infrared and thermography technology provides countless applications in different research and applied fields. The analysis of thermal changes and their monitoring is one of the popular usages of infrared technology which equally applies for long-term specimen observations or in contexts where chemical reactions are responsible for thermal changes. The proposed approach addresses thermal change-tracking of CO2 capture by brucite, a highly reactive magnesium dihydroxide mineral, in laboratory controlled conditions. Capture of CO2 by brucite is accompanied with thermal generation which commonly occurs in natural environments. An experiment was conducted in a carbonation cell at room temperature (22-23ºC) where gaseous CO2 is contacted with brucite while the process is monitored by means of a thermal camera positioned perpendicularly atop of reactor. Moreover, these thermal changes are recorded by thermocouples inserted at different locations in the carbonation cell. The slow reaction takes place over several hours during which the acquired data are stored to be post- processed after completion of the experiment. For the purpose of tracking spatially-resolved temperatures, thermal regions of interest from the infrared image were segmented first into several different sub-regions to represent local averaged zone temperatures. Then their corresponding changes were tracked over time. A color-based clustering was implemented for the segmentation in thermal images and for the smoothing of thermal fluctuations, namely, the Savitzky-Golay filter was used. Changes around 0.5ºC in amplitude were confirmed by the thermal sensors during the experiment.

The evaluation of temperature variation is very important issue relations in the fields of mechanical design, maintenance and advanced material. Development of carbon fiber or variable composites material is increasingly used in novel material especially aerospace field. One of the key factors in developing novel materials is finding alternative sources of power. Recent research trend is to develop self-actuating device from natural source. The main example is shape memory alloys(SMA), shape memory polymer(SMP) and etc. To develop the SMA or SMP, Thermal properties of material are important. Then the use of nondestructive testing(NDT) techniques is useful to get thermal data about novel materials. Infrared thermography(IRT) is convenient and useful method of NDT technique. However, IRT require various variables to get a proper data. In this research, we trying to reduce the number and find the emissivity of variables on bimaterial from 3D printing.

All objects above absolute zero (- 273 ℃) emit energy in thermal radiation form. This release of energy can be detected using infrared sensors, which were first applied in 1989 by infrared camera technology to measure the temperature of the surface of the object. Since then, infrared imaging cameras have become widely used in various industries. In this announcement, we present an overview of how infrared imaging cameras are applied in an industrial field. After reviewing cases of POSCO group and large sized office building, we were able to confirm that infrared imaging camera can be effective solution for equipment diagnosis.

Infrared thermography (IRT) is one of advanced nondestructive evaluation techniques based on the detection of infrared radiation using an infrared camera. Especially, IR thermography provides a quick, full-field and real-time inspection as well as a non-contact mode. Using those advantages, it is possible to perform thermographic analysis in the fields of railway applications such as brake disc, abnormal heating detection of components, mechanical testing monitoring, etc. In this investigation, current research activities in railway materials/components with IR thermography was introduced. For example, the electrical units of diesel electric locomotives were characterized for deterioration evaluation using infrared thermography technique. The high-speed infrared camera was used to measure surface temperature changes during tensile testing of railway steels. The damage evolution due to generation of hot spots on railway brake shoe or disc was successfully monitored using a high-speed IR camera. In this paper, the useful applications of IR thermography in railway areas was introduced and recent research results was also presented.

In this paper, infrared thermography (IRT) and ultrasonic C-scan (UT) were used to investigate basalt fiber reinforced polymer (BFRP), carbon fiber reinforced polymer (CFRP) and basalt-carbon fiber hybrid specimens subjected to impact loading. Of particular interest, two different hybrid structures including sandwich-like and intercalated stacking sequence were analyzed. Three different impact energies (5 J, 12.5 J and 25 J) were applied for the evaluation of the impact damage level in the different samples. The inspection by thermographic techniques of this type of laminates is an open matter to be discussed with the scientific audience. The results from pulsed phase thermography (PPT), principal component thermography (PCT) and partial least squares thermography (PLST) applied on raw thermal data were compared to understand the advantages and disadvantages of the two hybrid structures via a comprehensive analysis.

Based on the technique for determination of thermal constants in metals we have determined the heat conductivity and heat capacity of metal samples. The technique was adapted for application during standard mechanical test to determine the evolution of thermo mechanical properties of the samples under quasistatic loading. It gives us an opportunity to define the effect of inelastic deformation on the thermal constants of metals using infrared data treatment. The progress in the precision of proposed technique opens very promising perspectives for experimental measurements of thermo mechanical properties (for instance, configuration entropy) of deformed metals.

Pulse thermography and Laser Flash equipments are utilized in a complimentary way to measure thermal diffusivity of semitransparent materials. The best way to measure such a parameter is discussed when the heating source is not completely absorbed in a very thin layer of the front surface of the sample, but propagates through it and is eventually absorbed strongly on the back surface. This case appears when semitransparent materials are tested and their surfaces are blackened to increse the light absorption on the front side and the emissivity on the back. Introduction Pulse thermography is utilized in a complimentary way with laser flash technique to measure thermal diffusivity of semitransparent materials. The best way to measure such a parameter is discussed when the heating source is not completely absorbed in a very thin layer of the front surface of the sample, but propagates through it and is eventually absorbed strongly on the back surface. This case appears when semitransparent materials are tested and their surfaces are blackened to increse the light absorption on the front side and the emissivity on the back. Typical case is that of Thermal Barrier Coatings (TBCs) that are applied to protect components of gas turbines from high temperature combustion gases[1]. On the other hand the main component of TBCs, i.e. ZrO2 is semitransparent to near IR radiation. This is the wavelenght range where the laser heating source of the laser flash [2] equipment emits. Moreover, the characterization of TBCs at high temperatures is particularly interesting as the typical working temperature of gas-turbine is >1000 °C [3]. At these temperatures the radiative heat transfer becomes more and more relevant. The effect of blackening surfaces by a thin layer of graphite is considered [4]. Experiments are carried out at ambient temperature by means of a thermographic camera, at higher temperature in vacuum until 1200 °C and in ...

Recently, the demand for sheet metals has been increasing to reduce the size and weight of mechanical parts and structures. Various nondestructive inspection techniques have been studied to evaluate the soundness of sheet metal. The infrared thermography technique has advantages such as portability and large inspection area, but it is difficult to accurately measure the depth of defects in sheet metals. Therefore, to measure the depth of defects, this study has shown the correlation between the standard thermal contrast, defect diameter, defect depth, and thermal conductivity of various materials. In order to investigate the correlation between the standard thermal contrast and the diameter and depth of defects, defects were machined into 1-mm-thick sheet metal. The defect diameters were 2, 3, and 4 mm, and the depths were 0.3, 0.4, and 0.5 mm. The specimens were made of STS304, A1050, and C1020 to investigate the correlation between the standard thermal contrast and thermal conductivity of the materials. The maximum standard thermal contrast of the defects in the STS304 specimen was higher as the defect diameter was larger and the defect depth was shallower. In addition, the lower the thermal conductivity of the material, the higher the maximum standard thermal contrast. This relationship can be represented by an equation, and the depth of the defects estimated by the equation was compared with the actual depth of the defects.

Thermography is designed to record the surface temperature information of the photographed objects. It is difficult to efficiently extract the useful information related the defects presented in the building outside walls because it is hard to analyze many thermographs at a time. Principal component analysis (PCA) has been widely used to analyze the hyperspectral satellite images by generating the new image that is composed of major characteristics extracted from hundreds of bands contained in the hyperspectral images. In this study, a scheme is proposed by applying PCA on the collected thermographs such that large data can be limited into the few enhanced thermographs, and then object-based image segmentation is introduced to analyze those enhanced thermographs such that the boundaries of the segmented regions can be described and lied on those enhanced thermographs. The image segmentation presented in the paper can efficiently group those pixels with collecting similar surface temperatures into the same regions such that each thermography can be composed by few groups. In each segmented group, the average surface temperature of each segmented region can be used to replace the surface temperature recorded in each pixel. Furthermore, the environmental effects acting on the given thermal image can be estimated by the proposed model. In doing so, those regions with the highest surface temperature information can be considered as defects located on the exterior building layer. Different nondestructive testing methods are, then, applied to those identified locations to verify the processed results. From the experimental results, the proposed approach does offer a reliable way to locate the defects presented on the building exterior layers because the results obtained by applying impact echo method are almost the same with the processed results of the proposed approach.

This paper presents an evaluation of the areas of internal material damage caused by penetration by projectile of a sample of carbon fibre reinforced plastic (CFRP). The proposed method, which registers changes of temperature via thermal cameras on both sides of the sample under destructive testing, can complement the standard test methods conducted according to STANAG 2920. It also negates the need for further ballistic testing in an already damaged area of the material. The results were verified by non-destructive pulsed thermography testing, which is often used in tests of multilayer composite structures.

Recently, the defect detection is concerned as one of the important techniques used in the practical industrial fields. Among other nondestructive testing methods, infrared thermographic testing provides relatively more accurate data and less testing time. In this study, a steel plate specimen with FBHs (flat bottom holes) is tested by an infrared thermography system. Each raw of FBHs has the same depth while each column has the same diameter. When a specimen is heated by a halogen lamp whose power is controlled from 10% to 100% with 10% step, the thermographic images are obtained. The size of FBHs are compared using new proposed signal processing technique, the average of temperature differences method.

Defect inspection system for industrial applications takes the important portion. Non-destructive inspection method has been significantly improved. Infrared thermography, as one of method for non- destructive inspection, can provide relatively precise data and quick inspection time. This study, it was performed to measure defect according to the measurement limit of the nonvisible areas such as the back surface of the pipe using reflection plate. Proper material can be selected based on space limitation and thermal characteristics of target material that detection rate of defect can be improved. Detection of defect in non-visible area using the candidate materials for reflection plate was conducted.

In order to analyze the recent problems in thermal management, micro-scale thermography has been utilized to measure the thermophysical properties of energy materials and to detect the localized failure in semiconductors in the electronic industrial parts. Our equipment is widely applicable in the field of microscale thermography to achieve high-quality thermal imaging. The Infrared (IR) optical lens design has been optimized to each wavelength band of the photon type and the thermal type detectors of IR FPA. Typical applications to observe the freezing biological cells and the crystallization of organic mlecular crystals are reviewed together with the microscale laser flying spot method using the superimpose technique. The recent instrumentation of thermospectroscopy and the high temperature imaging systems are introduced with regard to the exothermic heat of chemical reaction in polymerization in microfluidics and the chemical heat storage process with molten salt to be utilized as the energy carier for the solar power plant.

Being able to perform full field easily noninvasive diagnostics for surveillance and monitoring of transport infrastructures and structures is a major preoccupation of many technical offices. Among all the existing electromagnetic methods, active infrared thermography [1] up to long-term thermal monitoring using uncooled infrared cameras is a promising technique [2]. Anyway, except for vision applications [3], there is few results available in literature (mainly on buildings) for outdoor measurements by infrared thermography. So, to complete, a review of specificities and constraints for in situ measurements on large scale structures is proposed. Key points identified are analyzed versus infrared system technological potential solutions available on the shelf or at laboratory level. To introduce transfer from laboratory conditions to real field, we will lean on some laboratory works on active thermography applied to quality control of reinforcement operations by gluing composite (CFRP) plates or tissues on concrete structure [4] or voids in pavement [5]. First, we will introduce and discuss the benefit of using numerical heat transfer modeling to optimize the control process [6,7] or generate virtual thermal image sequences to test post-processing methods [8_,9]. It will be followed by presentation and discussion on experiments carried out using laboratory specimen. Then, some post-processing analysis approaches will be discussed. Finally, considerations on requirements to move from laboratory conditions to real site field measurements will be proposed. Following the laboratory level presentation, a review of various experiments carried out, with an adapted infrared system, on different transport infrastructures or large scale element of Civil Engineering structures in outdoor conditions is given [10,11]. Raw results analysis is proposed. Processed data, obtained from few thermal images [12] to few days of experiments [10-11,13] up to several month of ...

Active infrared thermography is nowadays recognized as an efficient nondestructive evaluation tool to detect defects such as cracks, delaminations, or voids in a wide variety of materials. In this presentation we will focus on the characterization of vertical cracks using optical and ultrasonic excitation of the sample, as complementary techniques for open and kissing cracks, respectively. We will show that, for open cracks, optically excited thermography with a focused illumination is very well suited to characterize the thermal resistance (opening) and size of open vertical cracks. We present analytical calculations of the surface temperature distribution produced by infinite cracks, we analyze the optimum experimental conditions to characterize them and we point out a new methodology to deal with finite and thin cracks, based on discontinuous Galerkin finite elements. In the second part, we will show that ultrasound excited thermography is a very appropriate choice to characterize kissing cracks, as the rubbing of the contacting surfaces produces heat at the crack. We will describe the methodology we have developed to retrieve the geometry of the heat source distribution produced at the crack from surface temperature vibrothermography data. Experimental verification of the potential of infrared thermography with optical and ultrasonic excitation to characterize calibrated open and kissing vertical cracks will be presented.

Carbon fiber reinforced polymer (CFRP) is widely used in aviation and aerospace manufacturing due to its high specific strength, high specific modulus and high designability. In the production process of CFRP, some defects can’t be completely avoided. This paper focuses on the numerical simulation of pulsed infrared thermal non-destructive testing of delamination defects in CFRP. A two-dimensional model was established in the finite element analysis (FEA) to study the effect of defect size and defect depth on the defect informative parameters. Afterwards, an experiment was conducted to verify the results of numerical simulation and to find the detection limits of depth and size of delamination defects under the normal heating conditions.